What EPA's radon map says about Colleton County

Colleton County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Colleton County sits at the 20th percentile nationally for radon potential — above 20 of every 100 rated counties.

How Colleton County compares

About 39,259 people live in Colleton County, South Carolina, spread over 1,056.509 square miles. That works out to roughly 37 people per square mile. Among counties sharing Colleton County's EPA zone, it outranks 61% of them by population. Colleton County falls in EPA Radon Region 4, one of 736 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Colleton County

Colleton County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. Don't read Zone 3 as a pass for Colleton County — EPA's guidance to test every home makes no exception for counties predicted low.

Testing and mitigation in Colleton County

Mitigation cost doesn't depend on Colleton County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find South Carolina's state radon program

Colleton County's test kit answers today; a Airthings radon monitor keeps answering for Colleton County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

More on how this number was built

Colleton County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Colleton County carries, the zone explainer covers what it does and doesn't tell you about any one house.